排序方式: 共有38条查询结果,搜索用时 31 毫秒
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以酰胺-噁唑啉为辅助基团,在廉价的醋酸铜促进下,实现了酰胺衍生物C(sp2)—H键与芳基硫醇S—H键的脱氢偶联反应;以中等到优秀的产率(最高可达90%)简单高效地合成了一系列双硫化的酰胺衍生物.值得一提的是,底物范围并不局限于各种取代苯基酰胺化合物,吡啶基酰胺化合物也可以兼容.该反应的特点是:金属廉价、底物范围广、反应条件温和、无需外加配体、空气作为氧化剂、区域选择性好(仅酰胺基团邻位的C—H键发生反应,而噁唑啉基团邻位的C—H键不发生反应);此外,克级规模的反应表明了其在合成中的实用性. 相似文献
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Li H Liu L Zhao F Wang C Wang C Song Q Zhang WX Xi Z 《The Journal of organic chemistry》2012,77(10):4793-4800
The carbonylation of a 1-lithio-1,3-butadiene derivative with CO gave rise to a butadienyl acyllithio intermediate, which underwent an immediate intramolecular acyllithiation of the C═C double bond, affording a lithio cyclopentadienyl enolate. The X-ray structural analysis of the enolate revealed a dimer connected with a "Li(2)O(2)" four-membered ring. Subsequent intermolecular acylation of this enolate with acid chlorides afforded β-keto-3-cyclopentenones, γ-keto-2-cyclopentenones, or cyclopentadienyl ester derivatives. The stereo- and regioselectivity of the in situ generated lithio cyclopentadienyl enolate with various acid chlorides was investigated and analyzed, showing that the formation of the above products was significantly dependent on both the substituents on the butadienyl skeleton and the bulkiness of acid chlorides. 相似文献
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Fully or partially substituted 1-iodo- or 1-bromo-1,3-dienes could be readily lithiated using t-BuLi or n-BuLi to afford their corresponding 1-lithio-1,3-diene derivatives in quantitative yields. When these in situ generated lithium reagents were treated with organonitriles, depending on the substitution patterns of the butadienyl skeletons, substituted pyridines, pyrroles, and/or linear butadienyl imines were formed in good to excellent yields via N-lithioketimine intermediates. In the cases of 1,2,3,4-tetrasubstituted and 2,3-disubstituted 1-lithio-1,3-dienes, pyridine derivatives or linear butadienyl imines were generally formed depending on the reaction temperatures. When 1,2,3,4-tetrasubstituted 4-halo-1-lithio-1,3-dienes and 1,2-disubstituted 1-lithio-1,3-dienes were treated with organonitriles, pyrrole derivatives or linear butadienyl imines were obtained. Competition between 5-exo and 6-endo cyclization was found to be responsible for the formation of either pyrroles or pyridines. Selective elimination of RLi from the lithiated cyclic N-containing intermediates was observed. The order of elimination was found to be LiCl > Me3SiLi > LiH. 相似文献
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Xiaojuan Wang Wenxian Zhao Gaowei Li Jin Wang Guanjun Liu Lantao Liu Ruijuan Zhao Mincan Wang 《应用有机金属化学》2014,28(12):892-899
A family of enantiopure β‐aminoalcohols based on aziridine backbones were synthesized, and examined as chiral ligands for the copper(II)‐catalyzed asymmetric Henry reaction of aromatic aldehydes with nitromethane, giving β‐nitroalcohols in excellent yields (up to 93%) and moderate to good enantioselectivities (up to 82%). Moreover, possible transition states of the reaction are proposed. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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Chiral N-heterocyclic carbene (NHC) ligands having a 2,2'-bisquinoline-based C(2) symmetric skeleton were developed. The ligands exhibited good enantioselectivity in palladium-catalyzed intramolecular α-arylation of amides to give 3,3-disubsituted oxindoles. 相似文献
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Palladium-catalyzed insertion of activated alkynes into silacyclobutene derivatives proceeded smoothly to afford exo-alkylidenesilacyclohexadiene derivatives of unique structure with diversified conjugation systems in high isolated yields. Interesting regioselectivity of insertion, which afforded only one regioisomer or a mixture of two or more regioisomers, was also observed. 相似文献
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Yu N Wang C Zhao F Liu L Zhang WX Xi Z 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(18):5670-5679
Addition cyclization of 1,2,3,4-tetrasubstituted 1,4-dilithio-1,3-dienes (Type I) with four equivalents of various aromatic nitriles in the presence of hexamethylphosphoramide (HMPA) gives exclusively fully substituted pyridines in moderate to good yields. Similarly, trisubstituted pyridines can be prepared by the reaction of 2,3-dialkyl- or diaryl-substituted 1,4-dilithio-1,3-dienes (Type II) with nitriles. However, five- or six-membered-ring fused 2,3-disubstituted 1,4-dilithio-1,3-dienes (Type III) reacted with various aromatic and aliphatic nitriles without alpha-hydrogen atoms to afford tricyclic Delta1-bipyrrolines in high yields. The reaction of six-membered-ring fused 2,3-disubstituted 1,4-dilithio-1,3-diene (Type III) with 2-cyanopyridine afforded the corresponding pyridine, and no tricyclic Delta1-bipyrroline was observed. Seven-membered-ring fused dilithiodienes reacted with PhCN or trimethylacetonitrile to afford the corresponding pyridines in good yield. When 1,2,3,4-tetrasubstituted dilithio reagents (Type I) were treated with Me3SiCN, a tandem silylation/intramolecular substitution process readily occurred to yield siloles, whereas the reaction of 2,3-disubstituted dilithio reagents (Types II and III) with Me3SiCN gave rise to (Z,Z)-dienylsilanes with high stereoselectivity. These results revealed that the formation of tricyclic Delta1-bipyrrolines, pyridines, siloles, and (Z,Z)-dienylsilanes are strongly dependent on the substitution patterns of the dilithio butadienes and the nature of the nitriles employed. 相似文献